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The name Airstop says it all. Michelin's Airstop tubes use a proprietary butyl rubber so your tires keep their pressure longer. And, the reinforced valve stem seam is ultra sturdy, too.
Size: 700 x 18-23c
Schrader valves are identical to those found on car tires. These valves are generally used on hybrid and children's bikes. Presta valves, which are found on most road and off-road bikes, are longer and thinner and feature a threaded tip, which must be opened to inflate (turn counterclockwise).